The fundamental mechanism of heart muscle contraction is still very far from being clearly understood. In fact, even a clear quantitative description of how muscle contracts (i.e., phenomenological mechanics rather than the intracellular mechanism) remains to be attained. This proposal attempts to apply a few engineering techniques such as electronic servocontrol apparatus to facilitate analysis of the relation of muscle force to its length and the laser diffraction technique to analyze intracellular mechanical event (shortening and lengthening of the unitary element of muscle) simultaneously with a subtle force measurement. Tedious and demanding surgical skills will have to be combined with this elaborate technology, which is another salient feature of this proposal to advance our knowledge.